Add CSS override for banner (microsoft#3933)

* Add css override for banner

* remove merge conflict

python/packages/autogen-core/docs/src/_static/override-switcher-button.js

@@ -1,29 +1,36 @@
 // When body is ready
-document.addEventListener('DOMContentLoaded', function() {
-    // TODO: Please find a better way to override the button text in a better way...
-    // Set a timer for 3 seconds to wait for the button to be rendered.
-    setTimeout(async function() {
+document.addEventListener('DOMContentLoaded', async function() {
+
+    const styles = `
+    #bd-header-version-warning {
+        display: none !important;
+    }
+    `;
 
-        // Fetch version list
-        // https://raw.githubusercontent.com/microsoft/autogen/refs/heads/main/docs/switcher.json
-        const response = await fetch('https://raw.githubusercontent.com/microsoft/autogen/refs/heads/main/docs/switcher.json');
-        const data = await response.json();
+    // Fetch version list
+    // https://raw.githubusercontent.com/microsoft/autogen/refs/heads/main/docs/switcher.json
+    const response = await fetch('https://raw.githubusercontent.com/microsoft/autogen/refs/heads/main/docs/switcher.json');
+    const data = await response.json();
 
-        // Find the entry where preferred is true
-        const preferred = data.find(entry => entry.preferred);
-        if (preferred) {
-            // Get current rendered version
-            const currentVersion = DOCUMENTATION_OPTIONS.VERSION;
-            const urlVersionPath = DOCUMENTATION_OPTIONS.theme_switcher_version_match;
-            // The version compare library seems to not like the dev suffix without - so we're going to do an exact match and hide the banner if so
-            // For the "dev" version which is always latest we don't want to consider hiding the banner
-            if ((currentVersion === preferred.version) && (urlVersionPath !== "dev")) {
-                // Hide the banner with id bd-header-version-warning
-                document.getElementById('bd-header-version-warning').style.display = 'none';
-                return;
-            }
+    // Find the entry where preferred is true
+    const preferred = data.find(entry => entry.preferred);
+    if (preferred) {
+        // Get current rendered version
+        const currentVersion = DOCUMENTATION_OPTIONS.VERSION;
+        const urlVersionPath = DOCUMENTATION_OPTIONS.theme_switcher_version_match;
+        // The version compare library seems to not like the dev suffix without - so we're going to do an exact match and hide the banner if so
+        // For the "dev" version which is always latest we don't want to consider hiding the banner
+        if ((currentVersion === preferred.version) && (urlVersionPath !== "dev")) {
+            // Hide the banner with id bd-header-version-warning
+            const styleSheet = document.createElement("style");
+            styleSheet.textContent = styles;
+            document.head.appendChild(styleSheet);
+            return;
         }
+    }
 
+    // TODO: Please find a better way to override the button text...
+    setTimeout(async function() {
         // Get the button with class "pst-button-link-to-stable-version". There is only one.
         var button = document.querySelector('.pst-button-link-to-stable-version');
         if (!button) {